The actor, who was diagnosed with the illness earlier this month, is currently in stage 2 and not, as previously reported, in stage 4. He is currently undergoing aggressive treatment.
In an interview with Nightline, O'Neal admitted that his cancer diagnosis came as a surprise but has insisted that he is determined to make a full recovery.
"I wasn't prepared for it. I wasn't ready for it. But you never are," he said. "I just sort of chalked it up, you know, to bad luck."
O'Neal also revealed that he also has a cancerous melanoma on his nose, adding: "Welcome to Malibu and the sun."
The 70-year-old, who lost partner Farrah Fawcett to anal cancer in 2009, said that his relationship with the actress gave him strength to fight the disease.
"Farrah taught me that - about fighting it, fight a good fight," he said.
O'Neal will undergo a cryopathy procedure in the coming weeks, where doctors will freeze infected tissue in the hopes of stopping the spread of cancerous cells.
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